1. Trim ends from lettuces, keeping leaves attached to base. Rinse gently but thoroughly. Drain, then wrap in kitchen towels and chill about 15 minutes to crisp.
2. Meanwhile, in a small bowl, whisk together vinegar, chives, dill, salt, pepper, and oil.
3. Set each lettuce on its base in a shallow soup bowl (for upright varieties like Little Gem, first crack leaves near their base so they splay out). Tuck in chive pieces, dill sprigs, and whole flowers. Scatter with flower petals and radishes, if you like. Serve with dressing on the side.